Heretofore, calendars have been provided utilizing an inner slidable sheet or member containing numerals for registering with selective openings in an outer sheet to provide a single calendar which may be used year after year with certain manual adjustments. For example, U.S. Pat. No. 2,499,329 dated Feb. 28, 1950 is directed to a calendar having an outer relatively fixed sheet or cover with cutout portions or apertures therein for registering with numerals representing each day of a month and an inner slidable sheet containing the predetermined numerals thereon for registering with the apertures on the outer sheet for viewing to indicate the day of the month. In addition, the days of the week are shown on the inner slidable sheet or card for registering with the apertures. In order to use the calendar in U.S. Pat. No. 2,499,329 for an entire month it is necessary to remove the inner slidable card from the outer cover, and then reverse the inner card for reinsertion within the outer cover. As the days of the weeks are set forth on the inner slidable card, the days of the week cannot be printed in a fixed relation on the outer cover sheet.
U.S. Pat. No. 2,609,630 dated Sep. 9, 1952 also shows a calendar having an inner slidable card with numerals thereon for registering with a single large opening or aperture in the outer cover for viewing. The inner slidable card does not require removal and reversal for registering with the outer cover but does require a large width in which to present the various days of the month. As shown in the drawings of the '630 patent the inner card projects laterally outside of the outer cover a substantial distance in order to indicate certain days of a month. It is undesirable to require such a large width in order to operate and a viewing of a portion of the inner card extending outside the cover is not desirable.